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Performance of Stone Matrix Asphalt Pavements in Maryland. L. Michael G. Burke C. Schwartz AAPT 2003 Lexington, KY. Maryland’s First SMA 1992 First Superpave 1995. 2001. 2002. 1999. 2000. 1996. 1997. 1998. Since 1996 Maryland has been designing SMA with SGC. 76-22. 70-22.
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Performance of Stone Matrix Asphalt Pavements in Maryland L. Michael G. Burke C. Schwartz AAPT 2003 Lexington, KY
Maryland’s First SMA 1992 First Superpave 1995
2001 2002 1999 2000 1996 1997 1998 Since 1996 Maryland has been designing SMA with SGC
76-22 70-22 64-28 Since 1997 Maryland has been using PG Binders...
Ndesign 100 VTM 4.0 VMA 18.0 External 1.25 Internal 1.16
19.0 12.5 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075 GRADATION SPECIFICATION 19.0 mm 100 82-88 -60 20-28 14-20 9-11 12.5 mm 100 90-99 70-85 30-50 20-33 8-11 9.5 mm 100 100 70-90 30-50 20-30 8-13
COARSE AGGREGATE Gap-Graded Mixes Test Property LA Abrasion Loss, % Max. Flat & Elongated Particles, % Retained on the #4 Sieve Max. 3:1 5:1 PV Test Method T96 D4791 --- --- MSMT 411 Specification Limits 30 --- 20 5 8.5(d)
Hot Mix Asphalt Gap-Graded Plant Control VMA 18.0 Min. 17.0 Min. VTM 4.0 ±1.2 Ndes 100 AC 6.5 Min. ±0.4 Binder 70-22 Draindown % Max. Stabilizer By Weight of Total Mix % Specification 0.3 0.2 - 0.4 Plant Tolerance 0.3 Max. ±0.1 The Gap-Graded Specimen shall conform to the following
Rut Resistant Durable Skid Resistant Reduced Spray Reduced Hydroplaning Reduced Sound CHARACTERISTICS SuperpaveSMA
DECISION POINTS FOR USING SMA • 2000 ESAL’s per day • 55 mph
12.5 mm 19 mm
12.5 mm 19 mm
12.5 mm 19 mm
12.5 mm 19 mm
12.5 mm 19 mm CORRELATIONS • SMALL RANGE OF PERFORMANCE • SMALL RANGE OF MIX PROPERTIES
SUMMARY • Performance and material property data for 85 SMA projects • 1300 lane miles • Up to 10 years service life • Primarily 19 and 12.5 mm SMA mixes • Excellent performance: • Rutting: 0.04 inches/year (avg) • Roughness (IRI): 3.2 in/mile-year (avg) • Friction (FN): 1.3/year (avg)
SUMMARY • Inconclusive correlations between performance and mix properties • Too little variation/deterioration of performance • Too little variation in mix properties Many of the Maryland SMA sections look better today than when first opened to traffic!
SMA looks good... …Let’s use it!